Industrial production in Bacillus sp. of products of interest such as heterologous polypeptides, amino acids, carbohydrates etc., even when such a product is secreted into the medium, very often requires a costly purification step of the product from the culture medium. Contaminant polypeptides native to the Bacillus production host cell are secreted into the culture medium, and they may have to be removed e.g. in order to ensure the stability of the product, or to obtain a sufficient purity of the product. Typically, the native secreted contaminant polypeptides could be proteolytic enzymes, nutrient uptake factors, signal molecules etc.
Naturally, it is of considerable interest to the industrial producers to reduce the costs associated with product purification steps, indeed it would be of commercial value if one or more purification steps could be completely eliminated.